The social model of disability and the new sociology of childhood emphasize respectively the relevance of the environment to participation and the importance of quality of life. Such ideas can be readily understood by and shared among parents, young disabled people, professionals, and planners. They also make clearer what professionals are trying to do when supporting disabled children and their families. This article discusses these concepts and shows how they must be expressed in quantitative terms if they are to influence research, planning, and clinical practice.